One of the last great Fire-drakes of Middle-earth, Smaug rose to prominence by laying waste to the town of Dale and capturing the Dwarf-kingdom of the Lonely Mountain (Erebor) with all of its treasure. These events occurred some 150 years before the events of The Hobbit, and Smaug was already centuries old at the time. The Hobbit recounts the tale of a party of dwarves (consisting of a few of the original residents of the Lonely Mountain and their descendants), the hobbitBilbo Baggins, and their quest to recapture the mountain and kill the dragon. In the book, the dragon is sometimes called Smaug the Golden or Smaug the Magnificent.

Centuries spent sleeping atop his gold hoard have caused gold and gemstones to become embedded in the skin of Smaug's underside, augmenting the already impenetrable scales that covered most of his body; but when Bilbo observes Smaug in his lair, he discovers a small bare patch, of which a thrush tells Bard the Bowman, when Smaug later attacks Bard's native town of Esgaroth; whereupon the archer kills Smaug with an arrow. Among the items in Smaug's possession are the Arkenstone and a number of mithrilmail shirts, one of which was given to Bilbo by Thorin Oakenshield. In The Lord of the Rings, years later, the shirt saves Bilbo's kinsman, Frodo Baggins, from various injuries.

In Appendix A, section III, of The Return of the King under "Durin's Folk", Smaug is mentioned briefly as "the greatest of the dragons of his day". Having heard rumour of the great wealth of Erebor, he "arose and without warning came against King Thrór and descended on the mountain in flames." In this text, dragons are stated to reside in the wastes (Withered Heath) beyond the Grey Mountains, "making war on the Dwarves, and plundering their works". It can be inferred that Smaug came from this region.

As stated in the tale The Quest of Erebor, Gandalf knew that Smaug could pose a serious threat if used by Sauron, then dwelling in Dol Guldur in Mirkwood; assumed that Smaug would not recognize the scent of a Hobbit; and therefore asked Bilbo to accompany the dwarves.

Tolkien created numerous pencil sketches and two pieces of more detailed artwork portraying Smaug. The latter were a detailed ink and watercolour labelled Conversation with Smaug[3] and a rough coloured pencil and ink sketch entitled Death of Smaug.[4] While neither of these appeared in the original printing of The Hobbit due to cost constraints, both have been included in subsequent editions and Conversation with Smaug has been used extensively. Death of Smaug was used for the cover of an early UK paperback edition of The Hobbit.

From 1925 to 1945, Tolkien was a professor of Anglo-Saxon at Oxford University, and a prominent critic of and expert on Beowulf — on which he gave a lecture at the British Academy in 1936[5] and which he described as one of his "most valued sources" for The Hobbit.[6] Many of Smaug's attributes and behaviour in The Hobbit derive directly from the unnamed "old night-scather" in Beowulf: great age; winged, fiery, and reptilian form; a stolen barrow within which he lies on his hoard; disturbance by a theft; and violent airborne revenge on the lands all about. Smaug was intimately familiar with every last item within his hoard, and instantly noticed the theft of a relatively inconsequential cup by Bilbo Baggins. Tolkien writes that Smaug's rage was the kind which "is only seen when rich folk that have more than they can enjoy lose something they have long had but never before used or wanted." This theft of a cup, Smaug's knowledge of every item in the hoard, and the dragon's ensuing rampage, all echo the story of Beowulf.

Tolkien noted that "the dragon bears as name—a pseudonym—the past tense of the primitive Germanic verb smúgan,[8] to squeeze through a hole: a low philological jest."[6]

Smaug was depicted by Tolkien as an intelligent being capable of speech, easily pleased by flattery and fascinated by Bilbo's description of himself in riddles. This is also done in later film adaptations such as The Hobbit: The Desolation of Smaug. He is described as having "quite an overwhelming personality" and every time his eyes flash across Bilbo's invisible form, he feels almost compelled to tell him the truth about himself because of the hypnotic power within.

In the 1977 animated version of The Hobbit, Smaug was voiced by Richard Boone. In general, Smaug's design in the animated version is consistent with Tolkien's description, save for his face: for rather than the traditional reptilian look associated with dragons, Smaug's face in the animated version has distinctly cat-like features including fur, enlarged ears, and canine teeth. His hypnotic speech is absent, but his acute eyesight is portrayed by highbeam-like lights projected from his eyes.

On June 16, 2011, it was announced that Smaug would be voiced and interpreted with performance capture by Benedict Cumberbatch in Peter Jackson's three-part adaptation of The Hobbit,[9] wherein Smaug is presented with a long head, red-golden scales, a wyvern-like body, and piercing yellow-red eyes. The dragon speaks with Received Pronunciation with an underlying growl. The voice heard in the film is completely unaltered from Cumberbatch's vocal performance; only a mild digital rise in volume was added.[10][11][12] Smaug's design was also created with key frame animation, in addition to Cumberbatch's motion capture performance. Weta Digital employed its proprietary "Tissue" software which was honoured in 2013 with a "Scientific and Engineering Award" from the Academy of Motion Picture Arts and Sciences to make the dragon as realistic as possible. In addition, Weta Digital supervisor Joe Letteri said in an interview for USA Today that they used classic European and Asian dragons as inspirations to create Smaug.[13]

Smaug appears in the second film, The Hobbit: The Desolation of Smaug. In this adaptation, the weak spot in Smaug's armor is the result of one of his scales breaking off during his attack on Dale. He scares Bilbo into removing the One Ring, and reveals his knowledge of the growing threat from the Necromancer. Smaug then battles Thorin's small group of dwarves when they come to Bilbo's aid, before flying off to Lake-town, which he attacks in The Hobbit: The Battle of the Five Armies. He is killed by Bard with an elongated iron arrow.

Smaug was considered one of the highlights of the second film of the series, with several critics hailing him as cinema's greatest dragon.[14][15] Critics also praised the visual effects company Weta Digital and Cumberbatch's vocal and motion-capture performance for giving Smaug a fully realized personality. He made his final appearance in the film The Hobbit: The Battle of the Five Armies.[16][17]

In 2011, Smaug made his first appearance on the Fictional 15, the Forbes list of the 15 richest fictional characters. That year, he was ranked number 7 with an estimated net worth of $8.6 billion, whereas Scrooge McDuck was first with $44 billion.

In 2012, the magazine did a more in-depth analysis[18] on Smaug's wealth and concluded with a conservative estimate was $61 billion, which placed him comfortably atop the list.[19]Michael Noer, the author of this article, limited his estimate in order to keep Smaug's net value in line with living factual characters, notably Bill Gates and Carlos Slim. The estimates are tied directly to Smaug's size and the assumption that he lies directly on the largest part of his hoard. A more literal reading of Tolkien's text and comparison to historical instead of living factual persons (notably John D. Rockefeller or the Rothschild family) would result in a much higher estimate, as much as $870 billion, according to the article.

In the 2013 edition of the Forbes Fictional 15, Smaug placed 2nd on the list with a net worth of an estimated $54.1 billion falling behind Scrooge McDuck who was estimated to have a net worth of $65.4 billion.[20]

^Tolkien, J. R. R. "Appendix E – Writing and Spelling: I. Pronunciation of Words and Names". The Lord of the Rings.: "All these diphthongs were 'falling' diphthongs, that is stressed on the first element, and composed of the simple vowels run together. Thus ... au (aw) as in loud, how and not laud, haw."